1. Field of the Invention
The present invention relates to a thin film transistor and a method of fabricating an active layer thereof. More particularly, the present invention relates to a method of fabricating an active layer which can be directly performed in atmospheric air, a thin film transistor having the active layer, and a liquid crystal display.
2. Description of Related Art
Amorphous silicon transistor and low temperature polycrystalline transistor are the two major thin film transistors in today's active flat panel displays. However, since vacuum coating and photolithography processes are required for manufacturing such transistors, the cost of equipment, material, and process are substantially high. In particular, when the size of substrate gets larger and larger, how to reduce the manufacturing cost of these transistors becomes an important issue.
Accordingly, the research and development of new thin film transistor technique has been focused, wherein the method of fabricating thin film transistor using liquid process has become today's major subject. In recent years, methods of manufacturing II-VI compound, for example, ZnO, thin film transistor using liquid process is quick and simple, besides, no vacuum equipment is required for such processes. Thus, the manufacturing cost of thin film transistor can be reduced considerably. Moreover, the use of amorphous silicon transistor greatly improves the performance of the device, accordingly, the advantage of applying thin film transistor to low-cost and large-size product is greatly increased.
Regarding ZnO semiconductor, the existing methods for manufacturing thin film transistor with ZnO precursor solution is capable of evenly distributing ZnO nano particles in solvent, or the ZnO sol-gel solution is coated on a substrate by using a conventional method first, and then the residual solvent may be removed through conventional thermal process. Finally, recrystallization is performed. Good device characteristics can be obtained by using these methods. However, as the process temperatures are usually higher than 500° C., which may increase the manufacturing cost and adversely affect the throughput.